cypherpunks administrivia: no more reply-to header stripping

Riad S. Wahby rsw at
Wed May 14 10:18:44 PDT 2014


Until now, mailman has been stripping Reply-To: headers from messages
to the list. I've just turned this off.

Some webmail services (notably, Yahoo!) set the Reply-To: header and
include it in the headers signed with DKIM. Stripping Reply-To: thus
breaks the DKIM signature. In the case of Yahoo! this signature
breakage is especially problematic, because their DMARC policy is set
to reject. (In other words, messages with in the From:
header that fail both SPF and DKIM should be rejected by compliant
mail services, e.g., AOL, Gmail, Hotmail, Yahoo!)

Messages to the mailing list should pass SPF, since the envelope
sender domain for list messages is and I publish an
appropriate spf RR. However, any list subscriber who forwards mail to
another account will have broken SPF and an invalid DKIM signature,
which trips the DMARC policy and causes delivery failures.

I realize that this might cause some inconvenience, but I would prefer
to err on the side of successfully delivering messages whenever
possible. If you're using procmail and prefer the old behavior, the
following recipe should suffice:

* ^list-id.*
| formail -IReply-To


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